Improved strap for drop-presses



.0. MQBURNEY. 1 STRAP FOR DROP PRE$SES.

No. 40,349. Patented Oct. 20, 1863.

/' {W I l *1 UNITED STATES PATENT OFFICE.

CHARLES MGBUBNEY. OF ROXBUBY, MASSACHUSETTS.

lMPPtOVED STRAP FOR. DROP-PRESSES.

Specification forming part of Letters Patent No. 40.349, dated October 20, 1863.

To all whom/it may concern:

. Be it known that 1, CHARLES MGBURNEY, of Roxbury, in the county of Norfolk and State of Massachusetts, have invented certain improvements in the manufacture of straps for drop-presses, which are also applicable to the manufacture of machine-belting, of which'the following is a f all, clear, and exact description, reference being had to the accompanying drawings, making part of this specification, in Which-- Figure 1 represents the canvas employed, showingthe lines upon which it is cut up. Fig. 2 illustrates the manner in which the canvas is folded in making my improved strap.

Straps for drop-presses have usually been made of twoor more thicknesses of leather sewed or riveted together. After use for a short time these straps become, exceedingly hard and" rigid and lose the little elasticity which they original! y possess. They are then liable to break at the instant when the power is applied to elevate the weight, besides which they are originally very expensive.

My invention has for its object to produce a strap that shall possess a limited degree of elasticity, or such a capability of yielding on the application of the power to elevate the weight as to prevent the eflect'of the sudden application of force to the strap andmy invention consists of a belt or strap formed ofsuccessive layers of canvas cut diagonally across the piece and folded so as to bring both the warp and the weft threads diagonal to the length of the strap,-that the strain at no point may come directly upon the threads or in the direction of their length.

In thev manufacture of my improved semielastic strap I employ canvas, duck, or any. suitable woven goods having the requisite strength, which is coated upon both sides with the rubber compound in the ordinary way, so that the weight of the compound shallbe about eqnalto that of the cloth. It is then cut diagonally upon the lines a a, Fig. 1', and the strap is formed by folding over and over successive plies of the material, the folds being made-parallel to thelines a. a, Fig. 2, so as to bring the threads of the warp and weft diagonal to the strap in the direction of its length.

The strap is then confined between metallic plates and vulcanized by heating in any wellknown manner.

A strap thus made is found to possess a strength far surpassing that of a leather strap perior elasticity, which enables the strain to which it is subjected to be put uponit gradually; secondly, on account of the increased number of threads which assist to bear the strain.

In a rigid, non-elastic strap, as in the ease of one made of leather or of india-rubber and canvas put together in the ordinaryway-that is, with the folds parallel with the warpthreadsa-s all the strain is applied by a sudden jerk or twitch, and as the weight amounts oftentimes to several tons, this strain 'is immense. Where, on the other hand, the threads of the canvas run diagonally, the strip, inlieu of being rigid, is "rendered so elastic that the weight is thrown upon it verygradnally, and the strap is therefore submitted to a far less strain. At the same time that this is the case, the strap is also intrinsically much stronger, for while in the one case the warp-threads alone sustain the weight, in the other both the warp and the weft threads unite to give strength to the strap. The original cost (I this strap is also far less than that of theordinary leather strap.

The compound which I prefer for the man ufacture of my improved strap is made as fol lows: wenty-five pounds crude rubber, ten pounds white lead, and two pounds sulphur, the whole being ground together upon the ordinary heated rolls and spread upon the canvas in the well-known manner.

I do not, however, .confine myself to any particular compound or to any exact propor tions of the ingredients, as these may be varied to a considerable extent-without materially aflecting the result.

i What I claim as my invention, and desire to secure by Letters Patent, 1' s The improved strap or belt for drop-presses, composed of several plies of canvas cut diagonally and cemented together with vulcanized india-rubber, as set forth.

, CHARLES ,MCBURNEY.

Witnesses SAM. COOPER,

P. E. TEsonnMAoHER. 

